Health & Environmental Research Online (HERO)


Print Feedback Export to File
606446 
Journal Article 
The Effects of Far-red Light on Plant Growth and Flavonoid Accumulation in Brassica napus in the Presence of Ultraviolet B Radiation 
Gerhardt, KE; Lampi, MA; Greenberg, BM 
2008 
1 
Photochemistry and Photobiology
ISSN: 0031-8655
EISSN: 1751-1097 
84 
6 
1445-1454 
Flavonoid induction is regulated by complex signal transduction pathways involving cryptochrome, phytochrome and UVB photoreceptors. Previously, we identified the UVB-inducible flavonoids in Brassica napus cv. Topas leaves and showed that UVA affected accumulation of the quercetin (Q) and kaempferol (K) glycosides (Wilson et al. [2000] Photochem. Photobiol. 73, 678–684). In this study, we examined the effects of far-red light (FR, 700–780 nm) on UVB-mediated flavonoid accumulation in B. napus. Plants were grown under photosynthetically active radiation (PAR, 400–700 nm, 150 μmol m−2 s−1) plus a moderate level of FR (35 μmol m−2 s−1) for 14 days, and then transferred to five different irradiation regimes (PAR ± [UVA + UVB] + moderate, intermediate or low fluence FR) for 4 days. Kinetics of flavonoid accumulation were assessed via HPLC. Accumulation of flavonoids, in general, was suppressed by increasing the amount of FR in the spectrum. Furthermore, addition of UVB (290–320 nm) to the spectrum altered the flavonoid composition by causing significant changes in the quantities of individual flavonoids. The relative levels of acylated K glycosides were diminished whereas the relative levels of nonacylated Q glycosides increased dramatically. With UVB exposure there was a five-fold increase in the Q:K ratio. In contrast, increasing the level of FR in the presence of UVB decreased the Q:K ratio by half. [ABSTRACT FROM AUTHOR] Copyright of Photochemistry & Photobiology is the property of Blackwell Publishing Limited and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts) 
GROWTH (Plants); FLAVONOIDS; RUTABAGA; ULTRAVIOLET radiation; PHOTOSYNTHESIS